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Napierian spectral absorbance, <of a homogeneous non-diffusing layer>
Napierian spectral internal transmittance density
natural (Napierian) logarithm of the reciprocal of the spectral internal transmittance,
Note 1 to entry: The Napierian spectral absorbance has unit one.
Note 2 to entry: This entry was numbered 845-04-84 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-798 and 17-800 in CIE S 017:2011.